Adjustable fadeout control

ABSTRACT

A control system for use with an electrostatic type reproduction machine having a lamp and operating circuit therefor to dissipate the charge on the machine photoconductive surface at those times and places where developing is not desired. The aforesaid control system includes shift registers permitting timing of the lamp onoff cycle to be adjusted to prevent image carryover of adjoining component parts of the machine such as the document registration edge onto the copies produced. Selector switches are provided to permit the desired delay to be obtained as well as associate each delay with the different optical reduction modes.

United States Patent 1191 Reehil Jan. 14, 1975 [54] ADJUSTABLE FADEOUT CONTROL 3,661,452 5/1972 Hewes et al. 355 3 3,685,894 8/1972 Lux et a1 355/11 X [75] Inventor: Edward 3,714,519 1/1973 Swinea 317/141 s 3,721,908 3/1973 Jurjans 317/141 S X [73] Asslgnee Corporamn Stamford 3,778,147 12/1973 RCChll 61. al 355/11 x [22] Filed: 1973 Primary Examiner-Samuel S. Matthews 21 APPL 323 90 Assistant Examinerl(enneth C. Hutchison 52 us. (:1. 355/14, 35'5/7 1571 ABSTRACT [51] Int. Cl G03g 15/22 A control system for use with an electrostatic type re- [58] Field of Search 355/3 R, 14, 7; 328/37, production, machine having a lamp and operating cir- 328/43, 72; 235/92 SH; 307/141, 141.4, cuit therefor to dissipate the charge on the machine 141.8; 217/141 R, 141 S photoconductive surface at those times and places where developing is not desired. The aforesaid control [56] References Cited system includes shift registers permitting timing of the UNITED STATES PATENTS lamp on-off cycle to be adjusted to prevent image car- 2 519 184 8/1950 Grosdoff 328/45 X ryover of adjoining component parts of the machine 31091990 11 1963 Shuba....::::::::::::::: 328/43 Such as the document registration edge the 3,391,305 7/1968 Bradwin et al. 317/141 5 x ies Produced Selector Switches are Provided to Permit 3,392,350 7/1968 Griffin 317/141 8 UX the desired delay to be obtained as well as associate 3,602,589 8/1971 Dietz 355/14 each delay with the different optical reduction modes. 3,629,664 12/1971 Lajoie 307/141 x 3,638,047 1/1972 Klein 328/37 16 Clalms, 5 Drawing Flgures PATENTEU JAN 141975 sum 10F PATENTED JAN 1 4 9 sum 2 or :5

means O PATENTEU JAN 1 4 5 saw u or 1 ADJUSTABLE FADEOUT CONTROL This invention relates to an image fadeout control electrostatic reproduction machines, and particularly to an adjustable image fadeout control designed to provide optimum fadeout for such reproduction machines.

As is well known, in recent years the steadily increasing size of population and industry has resulted in a substantial increase in the amount of information that is recorded and through the use of copies, circulated. To meet this task, faster and faster copier/duplicators are appearing. However, as the operating speeds of copiers increase, problems attending the requisite higher operating speeds of these copiers and thier operating components are also generated.

As a solution for some problems entailed by high speed copying, latest machine concepts for copiers contemplate flash exposure of the original being copied coupled with a moving photoconductor material in the form of an endless belt. Charging of the photoconductor material and developing of electrostatic images formed through the aforesaid flash exposure is carefully controlled to accomplish solid area development with a minimum use of developer material, and one way of doing this is through the use of a fadeout lamp. The fadeout lamp, which is energized for predetermined periods during the copying cycle, serves to dissipate the charge in selected areas of the photoconductor, normally between images, to prevent development thereof. This in turn reduces the use or consumption of developer material as well as the load on the photoconductor cleaning apparatus; both quite significant in high speed machines which tend to use a great deal of developer material.

However, as will be appreciated, timing of the fadeout lamp on and off cycles is critical if efficient fadeout is to be effected without removing portions of the image being copied. While design of the reproduction machine, particularly the platen area and covers, can offset some of the timing criticality, accurate timing of the fadeout lamp cycle may nevertheless be necessary due to other machine design considerations. Additionally, the timing sequences for the fadeout lamp may change slightly with the various operating modes, i.e. image reductions, of the reproduction machine as well as due to machine usage and age.

It is therefore the principal object of this invention to improve electrostatic reproduction machines for effecting high speed development of line copy and solid areas with a minimum of waste of the developing material.

Another object of this invention is to utilize a lamp and lamp control circuit for controlling the presence of electrostatic charged areas on a photoconductive plate just prior to entry into a development zone thereby controlling those areas to be developed.

Another object of this invention is to permit continuous operation of an electrostatic charging device in an electrostatic reproduction machine thereby allowing high speed operation thereof.

It is a further object of the present invention to provide an improved control circuit for the photoconductive plate discharge device of an electrostatic type reproduction machine.

It is an object of the present invention to provide improved fadeout lamp control circuit means incorporating means to permit adjustment of the fadeout lamp timing cycle both for normal machine operation and for reduced size copying operation.

It is another object of the present invention to provide an improved control circuit for the image fadeout lamp in an electrostatic copying machine having means to permit a relatively rough first cut adjustment of the fadeout lamp cycle together with means to permit second fine adjustment of the fadeout lamp cycle tailored to each of the machine operating modes.

This invention relates to an electrostatic reproduction machine comprising, in combination, a movable photoconductive plate adapted to carry an electrostatic latent image thereon; means for charging the plate to enable the images to be produced thereon; developing means to develop the electrostatic image of the plate; a discharge device adapted when activated to discharge a charged area on the plate at a predetermined position in the travel of the plate, the discharge device being upstream 'of the development zone; control means adapted on a predetermined control signal to activate the discharge device and discharge portions of the plate normally outside the electrostatic images; and adjusting means to enable timing of the control signal to the control means to be varied whereby the area of the plate portions discharged may be optimized.

For a better understanding of the invention as well as other objects and further features thereof, reference is had to the following detailed description of the invention to be read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side view of an exemplary reproduction machine incorporating the improved fadeout lamp control circuit of the present invention;

FIG. 2 is an end view of the reproduction machine of FIG. 1 showing details of the machine platen and imaging station;

FIG. 3 is a schematic electrical diagram of a fadeout lamp control system for achieving selective development in the reproduction machine of FIG. 1;

FIG. 4 is a graphical representation of one fadeout lamp control signal; and

FIG. 5 is a schematic electrical diagram of the improved fadeout lamp control circuit of the present invention.

For a general understanding of the illustrated copier/reproduction machine 5, in which the invention may be incorporated, reference is had to FIGS. 1 and 2 in which the various system components for an exemplary reproduction machine are schematically illustrated. As in all electrostatic systems such as a xerographic machine of the type illustrated, a light image of a document to be reproduced is projected onto the sensitized surface of a xerographic plate to form an electrostatic latent image thereon. Thereafter, the latent image is developed with an oppositely charged developing material to form a xerographic powder image, corresponding to the latent image on the plate surface. The powder image is then electrostatically transferred to a support surface to which it may be fused by a fusing device whereby the powder image is caused permanently to adhere to the support surface.

In the illustrated machine, an original 4 to be copied is placed upon a transparent support platen 6 fixedly arranged in an illumination assembly generally indicated by the reference numeral 10 (at the left end of the machine as seen in FIG. 1). Illumination assembly 10 includes suitable flash lamps 3. While upon the platen, light generated by lamps 3 produces image rays corresponding to the informational areas on the original 4. The image rays are projected by means of an optical system 12 to expose the photosensitive surface of a xerographic plate. Conveniently, the exemplary reproduction machine 5 incorporates arrangements (not shown) to permit the size of the copy output to be reduced. These copy size reductions or machine operating modes may for example consist of full size 98% reduction, 74% reduction, and 65% reduction.

In the exemplary arrangement shown, the xerographic plate is in the form of a flexible photoconductive belt 7 arranged on a belt assembly generally indicated by the reference numeral 11. The surface of belt 7 comprises a layer of photoconductive material such as selenium on a conductive backing that is sensitized prior to exposure by means of a charging corona generator device indicated at 13.

The photoconductive belt assembly 11 is mounted upon a support bracket secured to the frame of the machine, belt 7 being driven in the direction of the arrow as shown in FIG. 2 at a constant rate. During movement of belt 7, the reflected light image 8 of the original 4 being copied on platen 6 is flashed upon the xerographic surface of belt 7.

The exposure of the surface of belt 7 to the light image discharges the photoconductive layer in the areas struck by light, whereby there remains on belt 7 a latent electrostatic image 8 in image of configuration corresponding to the light image projected from the original 4 on platen 6. As the belt surface moves, the electrostatic image 8 passes through a developing station 14 in which there is positioned a developer assembly 15 in the form of a series of magnetic brushes. Brushes 15 bring developing material in the form of toner into development relationship with the electrostatic latent image 8 on belt 7.

The developed electrostatic image on belt 7 is transferred, at transfer station 18,.to a sheet 16 of copy paper moving in synchronism with the moving belt 7. Copy sheets 16 are supplied by means of a suitable sheet transport mechanism generally indicated at 17, from a suitable paper supply generally indicated by the reference numeral 2.

Following transfer, the copy sheet 16 is separated from belt 7 and conveyed to a fuser assembly generally indicated by the reference numeral 19 wherein the developed and transferred xerographic powder image on the sheet 16 is permanently affixed thereto. After fusing, the finished copy is discharged from the machine at a suitable point, as for example tray 20.

Suitable drive means are provided to drive belt 7 in conjunction with the timing of the flashed images of the original being copied, to operate developing station 14, and provide copy sheets 16 in correct timed sequence to transfer station 18.

It is believed that the foregoing description is sufficient for the purposes of this application to show the general operation of an electrostatic copier using an illumination system constructed in accordance with the invention. For further details concerning the specific construction of the electrostatic copier, reference is made to U.S. Pat. No. 3,661,452, issued May 9, 1972, in the name of Hewes et al.

Reproduction machine 5 is adapted to copy originals and produce multiple copies thereof at a relatively high rate of speed. With provision for solid area coverage and a developing system which is adapted to supply relatively large amounts of toner particles to an electrostatic latent image, it is'desirable that means be provided for controlling development either directly or indirectly in order to develop only those portions of belt 7 on which the latent image exists. To this end there is provided a selective development control circuit 21, shown in FIG. 3, adapted to selectively dissipate the charges upon the belt 7 during those periods in which an original has not been exposed, i.e. between successive images 8 on belt 7. Additionally, the development control circuit also serves to dissipate charges arising on initial movement of the belt before the machine is conditioned to make the first exposure and during the production of the last copy immediately after the trailing edge of the last exposure.

Since the electrical inertia and hysteresis effects limit the Off-On response time for corotron energization, the charging corotron 13 for the machine 5 normally remains On during the complete printing cycle operation for the machine. Since belt 7 is continuously being charged, the development control circuit 21 is arranged to dissipate the charge in those areas of the moving belt 7 where exposure has not been provided in order to prevent development of these areas and consequently minimize both the loss of toner particles occasioned by developing a solidly charged area of the belt and the resulting load placed upon the belt cleaning system, shown in exemplary fashion as rotary brush 45.

Referring particularly to FIGS. 1 and 3, the control circuit 21 includes a discharge fluorescent lamp 22 which is mounted in a suitable housing 23 secured to the base of the machine and arranged so that the lamp 22 extends transversely across the path of movement of the belt 7 downstream of exposure station 9.

The end coils for the lamp 22 are connected respectively, to the secondary coils 26, 27 of a transformer 25. The primary coil 24 for the transformer 25 is connected to a suitable source of volt 60 cycle electrical power. The transformer 25 also includes a third secondary coil 28, which is adapted to step up the voltage and is connected to a full wave rectifier having positive and negative output terminals 29, 30, respectively. Preferably the output of the rectifier is approximately 300 volts d.c. with each of the transformer secondary coils 26, 27 capable of producing 6.3 volts.

With transformer secondary coils 26, 27 connected to the lamp coils, energization of the transformer primary coil 24 energizes the coils of lamp 22 tending to cause illumination thereof. However, with the center tap of the transformer secondary coil 26 being connected to the positive terminal 29 for the rectifier, the amount of power provided is sufficient to maintain the temperature of the gas in lamp 22 at a temperature just below the threshold necessary to cause illumination thereof. This condition of the lamp 22 is maintained during standby condition of the machine and at other periods during the machine cycle when the lamp is not in illumination condition. The lamp circuit however is arranged such that with a proper input signal thereto, additional energizing current is supplied to the two lamp coils and lamp 22 is triggered to full illumination condition.

By maintaining the standby energization thereof just slightly below the voltage necessary to produce full illumination, a relatively short duration pulse may be used to trigger the lamp 22 to cause full illumination thereof. The response time for the lamp to arrive at its full lumen output is correspondingly extremely short. These time periods, that is, the duration of the input triggering signal and the response time in which the lamp 22 achieves full illumination from a darkened or non-illumination condition and then reverts back again to a non-illumination condition can be measured in microseconds.

In order to accomplish this short duration illumination response time, the transformer secondary coil 27 is center tapped to the collector of a first transistor 32 which is normally maintained in a quiescent state. The emitter for transistor 32 is connected to the start shield 33 for the lamp 22 and has its other end connected to the negative terminal 30 of the rectifier. Conduction of the transistor 32 will provide a small d.c. voltage to the start shield 33 in order to accomplish an additional triggering voltage to the lamp 22 to effect the additional voltage bringing this lamp to full illumination condition.

In order to control conduction of the transistor 32, the base thereof is connected to the emitter of a second transistor 35 having its collector connected to a suitable source 34 ofd.c. current on the order of 24 volts. The bases for the transistors 32, 35 are connected respectively by diodes 36, 37 to the connection between the emitter for the transistor 32 and the lamp shield 33 in order to provide leakage compensation for the circuit. The transistor 35 is normally held in a nonconducting state; however, it is triggered into conduction by means of a signal pulse 56 in line 69 of the logic circuits, indicated generally by the reference numeral 39, for the reproduction machine 5 to which the development control circuit may be applied. The signal pulse 56 is connected to the base of the transistor 35 by way of the switching circuit 55 shown in FIG. 5, zener diode 40, and a variable resistor 41. The signal pulse 56 from the logic circuit 39 is adapted to drive the transistor 35 thereby rendering the transistor 32 conductive and connect the d.c. power supply 34 to the lamp shield 33 to provide the additional voltage for the lamp 22 to produce full illumination thereof.

Referring particularly to FIG. 4 of the drawings, the machine logic circuit 39 is arranged to generate at predetermined times during the copying cycle a relatively short pulse-like signal 56 for illuminating the lamp 22. The signal pulse 56 is generated between each two successive exposures on the belt 7 which, in the event multiple copies of a single document are being made, is the interval that normally results from the spacing between adjoining copies. The logic circuit 39 is also adapted to provide a signal pulse normally of different duration, (not shown) for illuminating the lamp 22 during the interval between the time the machine 5 is turned on (at which time belt charging and developer operation start) and the time just prior to the first illumination cycle of the lamps 3. A third control signal pulse (not shown) is also generated after the last flash of illumination produced by the lamps 3 to neutralize any belt charging and developer operation that occurs prior to the time the machine goes into its shutdown mode.

In effect then, during multiple copy operation, the development control discharge lamp 22 will be energized to discharge the portion of the belt 7 moving past the lamp during those times that a latent image is not traveling past the lamp. These times occur for the spaces between copies, before the first copy, and at the time that the trailing edge of the last copy has moved past the lamp and before the belt drive is terminated which occurs at shutdown condition of the machine. Discharge lamp 22 will remain energized during a single copy operation until the machine assumes a shutdown mode in order to completely discharge the charged areas of the belt. During multiple copy operation, however, discharge lamp 22 will be energized for short periods of time, i.e. those times between the trailirig edge of one latent image and the leading edge of a succeeding latent image. These short periods of time would occur once a second in the event that the machine is producing one copy a second. After the last copy of a multiple series of copies have been made, lamp 22 remains on until the belt drive terminates and the d.c. corotron supply is de-energized.

During those times that the discharge lamp 22 is illuminated, the uniform charge placed upon the belt 7 by the charge corotron 13 is erased since the light exposure by the lamp 22 will cause conduction of the photoconductor on the belt 7. Upon each of these occurrences, the area of the belt affected by the lamp 22 will not carry a charge and therefore will not be developed as these portions of the belt transverse the development station 14. With this arrangement it will be apparent only those portions of the belt which actually carry electrostatic latent images of information to be copied or reproduced will be treated at the development station 14. At all other times, especially during the start up of the machine and termination of the copying cycle, full development of uniform charged areas which do not carry information to be reproduced will be avoided. In this manner there is little loss of toner or developer material during a development process that is not necessary for machine use and reduced cleaning load on the belt cleaning brush 45. With the provision of the control circuit 21, the charging corotron 13 may be maintained in continuous energized condition and the discharge lamp control will, in effect, provide that necessary On-Off requirement for determining whether the belt will have or not have charged images thereon.

Referring now to FIG. 5 of the drawings, the control circuit 55 of the present invention includes a suitable pair of series related shift registers 60, 61, each driven by clock-like pulses in line 62 from the reproduction machine timing mechanism (not shown). Registers 60, 61 are reset or cleared on a signal from the machine logic circuit 39 provided on each print or copying cycle, the reset signal being provided through line 64.

The shift registers 60, 61 each have an input gate 60', 61, respectively, for receipt of the signal pulse 56 as will appear and plural output gates No. 29 on which the signal pulse 56, in predetermined timed progression from gate to gate, appears. The output gates No. 29 of register 60 are connected individually to corresponding terminals No. 2-9 of a suitable selector switch 68. Terminal No. 1 of switch 68 is connected directly to the line 69 bearing the control signal pulse from logic circuit 39 to permit register 60 to be bypassed. Line 69 also connects logic circuit 39 with input gate 60 of register 60.

The output terminal 70 of switch 68 is connected by line 71 with input gate 61 of shift register 61. Line 71 also connects directly to terminal No. l of each of mode switches 73, 74, 75, 76, effectively bypassing register 61 when terminal No. l of switches 73-76 is closed. The output gates No. 2-9 of register 61 are connected to corresponding terminals No. 2-9 of each mode switch 73, 74, 75, 76.

The output terminals 78 of mode switches 73-76 are connected to individual input terminals 81 of mode control switch 80. The switching state of mode control switch 80 is determined by the operating mode of reproduction machine 5, lines 82 serving to provide control signals from machine logic circuit 39 to set mode control switch 80 in the proper state. The output of mode control switch 80 is connected by line 84 to zener diode 40 of development control circuit 21.

Switches 68 and 73-76 each comprise a suitable manually settable multi-terminal switch. Mode switches 73-76 provide input of signal pulse 56 to mode control switch 80 in response to the different operating modes which the reproduction machine 5 is capable. For example, one mode may comprise the normal or unreduced size mode represented by switch 73. Other reduction modes are represented by switches 74, 75, 76, for example, a 98% reduction mode by switch 74, a 74% reduction mode by switch 75, and a 65% reduction mode by switch 76. As will be understood, the number of mode switches 73-76 varies in accordance to the number of different operating modes of which reproduction machine 5 is capable.

Referring now to FIG. 2 of the drawings, platen 6 has a plate-like part 87 extending along one edge thereof. The surface of plate 87 is slightly above the level of the platen glass 88 so that the edge 87 of plate 87 forms an abutment against which the document to be copied is abutted for registration or locating purposes. Where however the internal alignment of the machine optical system 12 is not exact, a portion of the registering plate 87 may be within the viewing area with the result that a relatively heavy line or area is formed along one edge of the copy. As will be understood, this undesirable edge printout may result in any one or all operating modes of reproduction machine 5.

To negate this undesirable edge printout, fadeout lamp 22 must be energized when the undesirable printout of registering plate 87 is within the operating area of lamp 22. However, the timing of the fadeout lamp operating cycle is critical if removal of portions of the copy image is to be avoided.

Machine logic circuit 39 is designed to provide the control signal pulse 56 for lamp 22 so as to energize lamp 22 for the exemplary present interval t,t (shown in solid lines in FIG. 4 of the drawing) during each copying cycle, the period !,-t being ordinarily sufficient to discharge, i.e. fadeout, substantially all the charge on belt 7 between adjoining images 8. However, the signal pulse interval t -t may not be exact enough, particularly in each of the machine operating modes, to remove the image carryover from registering plate 87.

In the exemplary reproduction machine 10 illustrated, any image carryover from registering plate 87 would appear along the leading edge 8' of the latent image 8 on belt 7 as seen in FIG. 2. If this occurs, the energization cycle of fadeout lamp 22 should be delayed slightly, so that the lamp 22 in effect starts later and remains on longer.

It should be understood that platen 6 is provided with a suitable cover 90 designed to shield the users eyes from extraneous light and hold the original 4 being copied in place on glass 88. The inside face of the cover 90 is provided with a white undercoating designed to eliminate or reduce any image carryover to belt 7 for those areas outside the periphery of the document 4 being copied. As a result, the turn on time, i.e. the starting time, of fadeout lamp 22 is not critical so long as the lamp 22 is energized sometime during the period between the images 8, i.e., the period where the image is of the undersurface of cover 90. As described earlier however, one side of the document 4 being copied is located against the registering edge 87 and at this point, since only the document and/or the plate 87 is visible to the optical system 12, the point at which lamp 22 is turned off is critical.

To permit the turn off point for lamp 22 to be set to the critical limits required, the circuit 55 is provided. Circuit 55 enables the signal pulse 56 from logic circuit 39 to be shifted or delayed in incremental steps-which in turn adjusts the point at which lamp 22 is turned on and off. This allows the lamp operating cycle to be set to pick up any image carryover from the registering plate 87 without erasing portions of the copy.

Referring to FIG. 5, where no offending image carryover from the registering plate 87 appears on the copies and hence no change or resetting of the control signal pulse 56 is necessary, switches 68 and 73-76 are set to close their respective terminals No. 1. This switch setting effectively bypasses shift rqisters 60, 61, and the signal pulse 56 from logic circuit 39 passes through line 69, switch 68, line 71 and the appropriate one of the switches 73-76 (depending on the state of mode control switch 80) to the base of transistor 35 as described heretofore. In this circumstance, fadeout lamp 22 is energized at point t, and deenergized at point in FIG.

Where, however, a black line or border appears along one edge of the copies indicating carryover of the image from registering plate 87, selector switch 68 of circuit 55 may be set to an appropriate one of the terminals No. 2-9 as for example, terminal No. 4. It will be understood that the proper setting of switch 68 and switches 73-76 is determined principally through trial and error, various settings being tried following which test copies are run to determine the efficacy of the settings chosen. Selector switch 68 serves normally to provide rough or first cut adjustment for all the machine operating modes while switches 73-78 provide fine adjustment for the individual machine operating modes.

With selector switch 68 adjusted to terminal No. 4, the control signal pulse from logic circuit 39 passes through register 60 where, after a predetermined delay, the signal appears at output gate No. 4 thereof. This is the signal pulse interval t t of FIG. 4. The delayed signal pulse from gate No. 4 passes via terminal 70 of switch 68 to line 71 where it may pass directly to mode control switch or through the second shift register 61 where a further delay is imposed, depending upon the setting of the appropriate mode switch 73-76. If, for example, mode switch 73 is set to close terminal No. 7 thereof, the delayed signal pulse 56, when the reproduction machine is programmed for operation in the normal mode, passes to shift register 61. After a further predetermined delay, the signal pulse emerges from output gate No. 7 of register 61 and passes via terminal 78 to mode control switch 80. From mode control switch 80, the delayed signal pulse 56 passes to zener diode 40 and the base of transistor 35 to operate fadeout lamp 22 as described earlier.

In a similar manner, the signal pulse in line 71, when reproduction machine 5 is in another of the machine operating modes as determined by the state of mode control switch 80, passes from the particular output gate of register 61 for which the operative mode switch 74, 75 or 76 is set to mode control switch 80. In this way shift register 61 imposes a selected delay in the fadeout lamp signal pulse 56 tailored to the specific operating mode of reproduction machine 5, this delay being in addition to or independent of that imposed by shift register 60 as reflected by the setting of switch 68.

While the turn-off point of fadeout lamp 22 has been described as critical in the exemplary reproduction machine described herein, it will be understood that the turn-on point of lamp 22 may instead be subjected to control.

While the invention has been described with reference to the structure disclosed, it is not confined to the details set forth, but is intended to cover such modifications' or changes as may come within the scope of the following claims.

What is claimed is:

1. In an electrostatic reproduction machine, a movable photoconductive plate adapted to carry an electrostatic latent image thereon, means for charging the plate to enable said images to be produced thereon; exposure means to produce latent electrostatic images on the moving plate to provide a plate with both image and non-image areas; developing means to develop the electrostatic images on the plate, and a discharge device adapted when activated to discharge a charged area on the plate at a predetermined position in the travel of the plate, the discharge device being upstream of the development zone, the combination of:

means to generate a control signal identifying said plate non-image areas;

control means adapted on said control signal to activate the discharge device and discharge non-image areas of the plate as said non-image areas move through said predetermined position, and adjusting means to enable application of said control signal to said means to be varied to adjust operation of said discharge device and assure discharge of all of said plate non-image areas by said discharge device without discharging image areas.

2. The electrostatic reproduction machine according to claim 1 in which said control means is adapted to activate said discharge device for a preset timed interval in response to said control signal,

said adjusting means being adapted to impose a selected time change on said control signal whereby to change activation of said discharge device and thereby displace the area discharged on said moving plate.

3. The electrostatic reproduction machine according to claim 2 in which said adjusting means includes at least one manually settable shift register through which said control signal may be passed to said control means.

4. The electrostatic reproduction machine according to claim 2 in which said adjusting means includes first and second shift registers, each of said first and second shift registers having an input gate for receipt of said control signal and a series of output gates;

means to index said first and second shift registers whereby to provide said control signal in timed sequcnce at different ones of said first and second shift register output gates;

a first selector switch associated with said first shift register adapted in one switch position to route said control signal from the input gate of said first shift register directly to the input gate of said second shift register and in a second switch position to route said control signal from a selected one of said first shift register output gates to the input gate of said second shift register; and

a second selector switch associated with said second shift register adapted in one switch position to route the control signal from the input gate of said second shift register to said control means. and in a second switch position to route said control signal from a selected one of said second shift register output gates to said control means.

5. The electrostatic reproduction machine according to claim 4 in which said reproduction machine includes means to provide at least one predetermined change in copy size,

said adjusting means including a second selector switch for each of said copy size reductions to permit application of the control signal to said control means to be varied for each of said copy size reductions.

6. In an electrostatic reproduction machine having a moving photoconductive plate adapted to be uniformly charged and to carry an electrostatic latent image thereon, developing means positioned at a development zone to develop the electrostatic image on the plate, and a discharge device adapted when activated to discharge a charged area of the plate at a predetermined position in the travel of the plate upstream of the development zone, the combination of:

means to generate a control signal identifying said plate non-image areas;

control means associated with said discharge device and responsive to said control signal to activate said discharge device for a predetermined interval whereby to discharge non-image areas of said plate as said non-image areas of said plate move through said predetermined position, and

means for displacing said control signal to change the time when said discharge device is energized and thereby vary the plate discharge location.

7. In an electrostatic reproduction machine, a movable photoconductive plate adapted to carry an elec trostatic latent image thereon, means for charging the plate to enable the electrostatic latent image to be produced thereon, exposure means to produce latent electrostatic images on the moving plate, developing means to develop the latent electrostatic images on said plate, and discharge means disposed in operative relation to said photoconductive plate and adapted when activated to discharge the area of the plate then in operative relationship with the discharge means, the combination of:

means for activating said discharge means on a preset control signal,

means for generating said control signal at predetermined non-imaging intervals during operation of said reproduction machine; said activating means actuating said discharge means in response to said control signals to discharge the area of said plate then in operative relationship with said discharge means, and

means for adjusting application of said control signal to said activating means to vary at least one boundary of the area discharged on the moving plate by said discharge means.

8. The electrostatic reproduction machine according to claim 7 including means for bypassing said control signal adjusting means whereby to avoid any change in application of said control signal to said activating means.

9. The electrostatic reproduction machine according to claim 7 in which said control signal adjusting means includes means providing at least one alternate path for said control signal adapted to delay input of said control signal to said activating means for a preset interval, and switching means for selectively routing said control signal through said one path.

10. The electrostatic reproduction machine accord ing to claim 7 in which said signal adjusting means includes means providing plural paths for said control signal, each of said paths being adapted to impose a progressively increasing delay on input of said control signal to said activating means, and

switching means for routing said control signal to a selected one of said signal paths.

[1. The electrostatic reproduction machine according to claim 7 in which said control signal adjusting means includes first means providing plural paths for said control signal, each of said paths being adapted to impose a progressively increasing first delay on input of said control signal to said activating means;

first switching means for routing said control signal through a selected one of said first paths;

second means in series relationship with said first means providing plural paths for said control signal, each of said second means paths being adapted to impose a progressively increasing second delay on input of said control signal to said activating means; and

second switching means for routing said control signal through a selected one of said second means paths whereby input of said control signal to said activating means may be delayed by an interval equal to the sum of the delays imposed by said first and second means.

12. The electrostatic reproduction machine according to claim 11 in which said reproduction machine has at last one reduction mode in which the size of the original being copied is reduced;

said control signal adjusting means including at least one additional second switching means for each of said reduction modes to permit application of said control signal to said activating means to be delayed for each of said reduction modes. 13. A control for fine tuning the operating cycle of a discharge lamp in an electrostatic reproduction machine so that at least one boundary of the area discharged by said lamp may be optimized, said lamp being arranged adjacent the path of the photoconductive plate of said machine and adapted when energized to discharge a band-like portion of said plate, said reproduction machine having means to generate an operating signal for energizing said lamp at least once during each reproduction cycle, and means for energizing said lamp in response to said signal, comprising:

shift register means between said signal generating means and said lamp energizing means, said shift register means having an input gate for receipt of said signal from said signal generating means and a plurality of signal output gates;

means to drive said register means to provide progressively delayed signals at each of said register means output gates; and

switching means for selectively connecting said shift register means output gates with said lamp energizing means. 14. The control according to claim 13 including second shift register means between said switching means and said lamp energizing means, said second shift register means having an input gate for receipt of said signal from said switching means and a plurality of signal output gates,

means to drive said second shift register means to provide progressively delayed signals at each of said second shift register means output gates, and

second switching means for selectively connecting said second shift register means output gates with said lamp energizing means.

15. The control according to claim 14 in which said first and second switching means are individually settable to bypass the shift register means associated therewith.

16. The control according to claim 14 in which said reproduction machine includes at least two operating modes, and second switching means for each of said reproduction machine operating modes.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,860,338 Dated January 14, 1975 Inventor(s) Edward G- Ree'hil It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 9, line 40 after "said" insert control Signed and sealed this 1st day of April 1975.

(SEAL Attest:

'. c. :iARsHALL DANN Commissioner of Patents RUTH C. MASON and Trademarks Attesting Officer FORM (169) v USCOMM-DC 60376-1 69 ".5. GOVIINUINT PRINTING OFFICE 2 1.. OS-3l.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,860,338 Dated Januarv 14, 1975 lnv nt fl Edward (L Ree'hil It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 9, line 40 after "said" insert control Signed and sealed this 1st day of April 1975.

(839.1.) Attest:

C. Z-"ZARSHALL DANN RUTH C. PIASOIT Commissioner of Patents Arresting Officer and Trademarks Po'wso uscoMM-oc cor/apes i ".8. GOVIINIINT IIINTI II|CI 1 I... 0-in-3, 

1. In an electrostatic reproduction machine, a movable photoconductive plate adapted to carry an electrostatic latent image thereon, means for charging the plate to enable said images to be produced thereon; exposure means to produce latent electrostatic images on the moving plate to provide a plate with both image and non-image areas; developing means to develop the electrostatic images on the plate, and a discharge device adapted when activated to discharge a charged area on the plate at a predetermined position in the travel of the plate, the discharge device being upstream of the development zone, the combination of: means to generate a control signal identifying said plate non-image areas; control means adapted on said control signal to activate the discharge device and discharge non-image areas of the plate as said non-image areas move through said predetermined position, and adjusting means to enable application of said control signal to said means to be varied to adjust operation of said discharge device and assure discharge of all of said plate non-image areas by said discharge device without discharging image areas.
 2. The electrostatic reproduction machine according to claim 1 in which said control means is adapted to activate said discharge device for a preset timed interval in response to said control signal, said adjusting means being adapted to impose a selected time change on said control signal whereby to change activation of said discharge device and thereby displace the area discharged on said moving plate.
 3. The electrostatic reproduction machine according to claim 2 in which said adjusting means includes at least one manually settable shift register through which said control signal may be passed to said control means.
 4. The electrostatic reproduction machine according to claim 2 in which said adjusting means includes first and second shift registers, each of said first and second shift registers having an input gate for receipt of said control signal and a series of output gates; means to index said first and second shift registers whereby to provide said control signal in timed sequence at different ones of said first and second shift register output gates; a first selector switch associated with said first shift register adapted in one switch position to route said control signal from the input gate of said first shift register directly to the input gate of said second shift register and in a second switch position to route said control signal from a selected one of said first shift register output gates to the input gate of said second shift register; and a second selector switch associated with said second shift register adapted in one switch position to route the control signal from the input gate of said second shift register to said control means, and in a second switch position to route said control signal from a selected one of said second shift register output gates to said control means.
 5. The electrostatic reproduction machine according to claim 4 in which said reproduction machine includes means to provide at least one predetermined change in copy size, said adjusting means including a second selector switch for each of said copy size reductions to permit application of the control signal to said control means to be varied for each of said copy size reductions.
 6. In an electrostatic reproduction machine having a moving photoconductive plate adapted to be uniformly charged and to carry an electrostatic latent image thereon, developing means positioned at a development zone to develop the electrostatic image on the plate, and a discharge device adapted when activated to discharge a charged area of the plate at a predetermined position in the travel of the plate upstream of the development zone, the combination of: means to generate a control signal identifying said plate nonimage areas; control means associated with said discharge device and responsive to said control signal to activate said discharge device for a predetermined interval whereby to discharge nonimage areas of said plate as said non-image areas of said plate move through said predetermined position, and means for displacing said control signal to change the time when said discharge device is energized and thereby vary the plate discharge location.
 7. In an electrostatic reproduction machine, a movable photoconductive plate adapted to carry an electrostatic latent image thereon, means for charging the plate to enable the electrostatic latent image to be produced thereon, exposure means to produce latent electrostatic images on the moving plate, developing means to develop the latent electrostatic images on said plate, and discharge means disposed in operative relation to said photoconductive plate and adapted when activated to discharge the area of the plate then in operative relationship with the discharge means, the combination of: means for activating said discharge means on a preset control signal, means for generating said control signal at predetermined non-imaging intervals during operation of said reproduction machine; said activating means actuating said discharge means in response to said control signals to discharge the area of said plate then in operative relationship with said discharge means, and meaNs for adjusting application of said control signal to said activating means to vary at least one boundary of the area discharged on the moving plate by said discharge means.
 8. The electrostatic reproduction machine according to claim 7 including means for bypassing said control signal adjusting means whereby to avoid any change in application of said control signal to said activating means.
 9. The electrostatic reproduction machine according to claim 7 in which said control signal adjusting means includes means providing at least one alternate path for said control signal adapted to delay input of said control signal to said activating means for a preset interval, and switching means for selectively routing said control signal through said one path.
 10. The electrostatic reproduction machine according to claim 7 in which said signal adjusting means includes means providing plural paths for said control signal, each of said paths being adapted to impose a progressively increasing delay on input of said control signal to said activating means, and switching means for routing said control signal to a selected one of said signal paths.
 11. The electrostatic reproduction machine according to claim 7 in which said control signal adjusting means includes first means providing plural paths for said control signal, each of said paths being adapted to impose a progressively increasing first delay on input of said control signal to said activating means; first switching means for routing said control signal through a selected one of said first paths; second means in series relationship with said first means providing plural paths for said control signal, each of said second means paths being adapted to impose a progressively increasing second delay on input of said control signal to said activating means; and second switching means for routing said control signal through a selected one of said second means paths whereby input of said control signal to said activating means may be delayed by an interval equal to the sum of the delays imposed by said first and second means.
 12. The electrostatic reproduction machine according to claim 11 in which said reproduction machine has at last one reduction mode in which the size of the original being copied is reduced; said control signal adjusting means including at least one additional second switching means for each of said reduction modes to permit application of said control signal to said activating means to be delayed for each of said reduction modes.
 13. A control for fine tuning the operating cycle of a discharge lamp in an electrostatic reproduction machine so that at least one boundary of the area discharged by said lamp may be optimized, said lamp being arranged adjacent the path of the photoconductive plate of said machine and adapted when energized to discharge a band-like portion of said plate, said reproduction machine having means to generate an operating signal for energizing said lamp at least once during each reproduction cycle, and means for energizing said lamp in response to said signal, comprising: shift register means between said signal generating means and said lamp energizing means, said shift register means having an input gate for receipt of said signal from said signal generating means and a plurality of signal output gates; means to drive said register means to provide progressively delayed signals at each of said register means output gates; and switching means for selectively connecting said shift register means output gates with said lamp energizing means.
 14. The control according to claim 13 including second shift register means between said switching means and said lamp energizing means, said second shift register means having an input gate for receipt of said signal from said switching means and a plurality of signal output gates, means to drive said second shift register means to provide progressively delayed signals at each of said Second shift register means output gates, and second switching means for selectively connecting said second shift register means output gates with said lamp energizing means.
 15. The control according to claim 14 in which said first and second switching means are individually settable to bypass the shift register means associated therewith.
 16. The control according to claim 14 in which said reproduction machine includes at least two operating modes, and second switching means for each of said reproduction machine operating modes. 